The invention pertains to the field of N-phenyl-N-(4-piperidinyl)amides having potent analgesic activity. A number of patents disclose certain N-phenyl-N-(4-piperidinyl)amides having analgesic activity such as, for example, U.S. Pat. Nos. 3,164,600; 3,998,834; 4,179,569; 4,584,303; and 4,167,574. The analgesic compounds of this invention differ structurally from the prior art compounds by the particular N-substituent on the piperidine ring, i.e., the "X" function indicated in the hereafter formula (I) compounds. In general, they also differ by their relatively short durations of analgesic action, ranging from the ultra short to medium range, and their non-hepatic means of inactivation. The invention also provides certain novel synthetic intermediates for making formula (I) compounds.